Color imaging devices, color image forming methods, and color image data processing methods

ABSTRACT

Color imaging devices, color image forming methods, and color image data processing methods are described. According to one embodiment, a color imaging device includes interface circuitry configured to access color image data comprising a plurality of initial values for a plurality of pixels of a first color space, translating circuitry coupled with the interface circuitry and configured to receive the initial values and to provide a plurality of respective translated values responsive to the received initial values, color space conversion circuitry coupled with the translating circuitry and configured to convert the translated values to a plurality of respective converted values of a second color space different than the first color space, and an image engine coupled with the color space conversion circuitry and configured to form a color image using the converted values of the second color space.

BACKGROUND

[0001] Computer systems including personal computers, workstations, handheld devices, etc. have been utilized in an increasing number ofapplications at home, the workplace, educational environments,entertainment environments, etc. Peripheral devices of increasedcapabilities and performance have been developed and continuallyimproved to extend the functionality and applications of computersystems. For example, imaging devices, such as printers, haveexperienced significant advancements including refined imaging, fasterprocessing, and color reproduction.

[0002] Color imaging devices are becoming increasingly popular as thedesire for color imaging capabilities continues to increase. Forexample, personal imaging of color photographs, documents, graphics,etc. is becoming increasingly popular. Inkjet printer and color laserprinter designs have made remarkable progress in an effort toaccommodate the desire for improved color imaging capabilities.

[0003] In general, color imaging devices perform color separationprocessing to convert color image data from an initial color space to aproper output color space to accurately provide reproduction of imagesusing the color imaging devices. Color separation processing includingcolor space conversion provides the color image data to be imaged in anappropriate color space for accurate color reproduction. Some colorseparation processes reduce or minimize the amount of hardware andprocessing used to implement color space conversion. Color separationmethods using interpolation reduce processing complexity and hardwarerequirements. Interpolation may utilize a plurality of interpolationregions to generally identify the location of a desired converted valuefor a respective input value. However, some interpolation regions mayhave increased sensitivity to interpolation resulting in an increasednumber of inaccuracies in resultant or outputted images.

DESCRIPTION OF THE DRAWINGS

[0004]FIG. 1 is a functional block diagram of a color imaging deviceaccording to one exemplary embodiment.

[0005]FIG. 2 is a functional block diagram of color space convertercircuitry according to one exemplary embodiment.

[0006]FIG. 3 is an illustrative representation of color image dataduring different processing points within color space convertercircuitry according to one embodiment.

[0007]FIG. 4 is a functional block diagram of a color space convertercore according to one exemplary embodiment.

[0008]FIG. 5 is a flow chart illustrating exemplary processing of colorimage data within the color imaging device according to one exemplaryembodiment.

DETAILED DESCRIPTION

[0009] According to one embodiment, a color media imaging devicecomprises interface circuitry configured to access color image datacomprising a plurality of initial values for a plurality of pixels of afirst color space, translating circuitry coupled with the interfacecircuitry and configured to receive the initial values and to provide aplurality of respective translated values responsive to the receivedinitial values, color space conversion circuitry coupled with thetranslating circuitry and configured to convert the translated values toa plurality of respective converted values of a second color spacedifferent than the first color space, and an image engine coupled withthe color space conversion circuitry and configured to form a colorimage using the converted values of the second color space.

[0010] According to another embodiment a color imaging device comprisesmeans for interfacing for accessing color image data comprising aplurality of initial values for a plurality of pixels of a first colorspace, means for translating for receiving the initial values and forproviding a plurality of respective translated values responsive to thereceived initial values, means for color space conversion for convertingthe translated values to a plurality of respective converted values of asecond color space different than the first color space, and means forimaging for forming a color image using the converted values of thesecond color space.

[0011] According to an additional embodiment, an article of manufacturecomprises processor-usable media comprising programming configured tocause processing circuitry to access color image data for a plurality ofpixels of a first color space and corresponding to an image, whereinindividual ones of the pixels are one of a plurality of pixel types,translate the provided color image data of the first color spaceproviding translated color image data for the pixels comprising apredetermined pixel type, convert the translated color image data toprovide color image data of a second color space for the pixelscomprising a predetermined pixel type, and output the color image dataof the second color space for use in the generation of color images.

[0012] According to still another embodiment, a color image formingmethod comprises providing a color media imaging device, providing colorimage data for a plurality of pixels of a first color space andcorresponding to an image, wherein individual ones of the pixels are oneof a plurality of pixel types, translating the color image data of thefirst color space providing translated color image data for the pixelscomprising a predetermined pixel type, color space converting thetranslated color image data of the first color space to provide colorimage data of a second color space for the pixels comprising apredetermined pixel type, and providing a plurality of colorants uponmedia according to the color image data of the second color space toform an image.

[0013] According to an additional embodiment, a color image dataprocessing method comprises providing color image data for a pluralityof pixels of a first color space and corresponding to an image, whereinindividual ones of the pixels are one of a plurality of pixel types,translating the provided color image data of the first color spaceproviding translated color image data for the pixels comprising apredetermined pixel type, color space converting the translated colorimage data to provide color image data of a second color space for thepixels comprising a predetermined pixel type, and outputting the colorimage data of the second color space for use in the generation of colorimages using a color imaging device.

[0014] Referring to FIG. 1, an exemplary configuration of a colorimaging device according to one possible embodiment is depicted withrespect to reference character 10. In one embodiment, color imagingdevice 10 is configured to form hard images including physicallyrendering color images upon output media (e.g., device 10 may comprise acolor laser printer) and be referred to as a color media imaging device.In other hard imaging embodiments, device 10 may be implemented as acopier, facsimile machine, multiple-function peripheral device, or anyother device configured to physically render color images upon media.Exemplary media includes paper sheet media, paper roll media, labels,transparencies, etc. In further exemplary embodiments, color imagingdevice 10 provides color conversion operations described herein with nohard imaging, for example, to provide image data for use in displayingimages upon a monitor, color display, projector, or other displaydevice, or in applications wherein hard imaging is not desired.

[0015] In the depicted exemplary hard imaging device configuration,color imaging device 10 comprises interface circuitry 12, a formatter14, a storage device 15, color space converter circuitry 16, and animage engine 18. The depicted configuration is presented to illustrateexemplary aspects of embodiments of the invention and otherconfigurations are possible including more, less or alternativecomponents (e.g., image engine 18 may be omitted in embodiments notgenerating hard images).

[0016] Interface circuitry 12 is configured to access color image datato be imaged using device 10. Color image data may be provided in anyusable format, including, for example, a common system-leveldescription, print language (e.g., PCL, Post Script, etc.), graphicalimages (e.g., JPEG), raw data or in any format capable of being used togenerate images. Interface circuitry 12 may comprise a network interfacecard (NIC), parallel connection, USB port, disk drive circuitry or anyother configuration capable of accessing data.

[0017] Interface circuitry 12 may access color image data from anyappropriate source. For example, the exemplary depicted interfacecircuitry 12 is coupled with external devices (e.g., host, privatenetwork, public network, etc.) and may access color image datatherefrom. Interface circuitry 12 may also access internally generatedcolor image data in another possible configuration.

[0018] In one embodiment, accessed color image data comprises aplurality of initial values for a plurality of pixels of a color imageand provided according to a first or initial color space. Initial orinput data or values refer to data or values prior to translating orcolor space conversion described below. The initial color space may be adevice-dependent or device-independent color space and may be RGB, CMY,CMYK, or other appropriate color space. In one exemplary arrangementdescribed herein, an initial color space is a device-independent CMYcolor space.

[0019] Formatter 14 is in communication with interface circuitry 12 andis configured to process color image data received from interfacecircuitry 12. In one embodiment, formatter 14 renders color image datafrom a print language format into tone information at a pixel-level.Other rendering or processing of color image data is possible. Forexample, additional processing may occur with respect to providing colorimage data into a common color space if color image data of differentcolor spaces is present.

[0020] Storage device 15 is configured to store electronic data and/orprogramming such as executable instructions (e.g., software and/orfirmware), data, or other digital information and may includeprocessor-usable media. Exemplary processor-usable media includes anyarticle of manufacture which can contain, store, or maintainprogramming, data and/or digital information for use by or in connectionwith an instruction execution system including processing circuitry(e.g., formatter 14 or other processing circuitry of device 10) in theexemplary embodiment. For example, exemplary processor-usable media mayinclude any one of physical media such as electronic, magnetic, optical,electromagnetic, infrared or semiconductor media. Some more specificexamples of processor-usable media include, but are not limited to, aportable magnetic computer diskette, such as a floppy diskette, zipdisk, hard drive, random access memory, read only memory, flash memory,cache memory, and/or other configurations capable of storingprogramming, data, or other digital information.

[0021] Executable instructions may be stored within storage device 15 toprovide image data translation operations and/or image data color spaceconversion operations according to some embodiments. Appropriateprocessing circuitry of device 10 (e.g., formatter 14) may execute theexecutable instructions to provide the translation, color spaceconversion, and/or other processing of the image data. Exemplarytranslation and color space conversion operations of image data aredescribed further below.

[0022] Color space converter circuitry 16 is configured to perform colorconversion operations wherein the color image data is converted from theinitial color space to one or more output or other color space inaccordance with an exemplary embodiment of the invention. Additionaldetails of color space converter circuitry 16 according to oneembodiment are shown in FIG. 2 and are described below.

[0023] Image engine 18 is configured to physically render color imagesupon output media including providing a plurality of colorants uponmedia according to provided color image data. In one exemplary printerarrangement, image engine 18 is configured as a printer engine of colorimaging device 10. At least some configurations of image engine 18include a development assembly configured to provide one or morecolorant marking agent in the form of the image and a fusing assemblyconfigured to affix the marking agent(s) to the media. Marking agentsinclude dry toner, liquid inks, etc. Other arrangements are possible andimage engine 18 may be embodied in any configuration capable ofgenerating hard color images upon media.

[0024] Referring to FIG. 2, exemplary color space converter circuitry 16to convert the color space of color image data is shown. The depictedcircuitry 16 is arranged to illustrate exemplary aspects of theinvention and includes translating circuitry 20, a color space convertercore 22, and translating circuitry 24 corresponding to different stagesof circuitry 16. Translating circuitry 20 may be referred to as input(or pre) translating circuitry and translating circuitry 24 may bereferred to as output (or post) translating circuitry. The indicatedcomponents of circuitry 16 are implemented using an Application SpecificIntegrated Circuit (ASIC) in one arrangement. Other configurationsand/or implementations are possible to convert color image data betweendifferent color spaces.

[0025] Color image data is received at the left side of circuitry 16from formatter 14 in the illustrated exemplary configuration. Colorimage data is provided to the left side of circuitry 16 in an initialcolor space. For example, color image data may be provided as deviceindependent CMY data comprising a plurality of 24 bit tripletsindividually including 8 bits of cyan data, 8 bits of magenta data, and8 bits of yellow data for respective pixels of an image.

[0026] In one embodiment, color space converter circuitry 16 processesindividual colorants in series. For example, the 24 bits of input colorimage data may be serially processed to provide converted color imagedata of the output color space for individual colorants in series. Inone example wherein the output color space comprises CMYK, circuitry 16may first process the triplet data to obtain the cyan colorantinformation, next process the triplet data to obtain the magentacolorant information, next process the triplet data to obtain the yellowcolorant information, and finally process the triplet data to obtain theblack colorant information for the individual pixel locations. Inanother embodiment, a plurality of circuits 16 may be provided inparallel and corresponding to respective colorants to providesimultaneous processing of the color image data to provide informationregarding respective individual colorants in parallel. Regardless ofserial or parallel processing, color space conversion processing (e.g.,translating and/or converting) may occur on a pixel-by-pixel basis in atleast one embodiment.

[0027] The pixels of color image data for a given image may include aplurality of different pixel types. In one example, an image to beformed upon a single sheet of media may comprise text data, line artdata, and graphical data. In some embodiments of the invention, colorspace converter circuitry 16 operates to process pixels differentlycorresponding to the respective pixel types as described further below.A plurality of pixel identifiers (e.g., object types) may be associatedwith respective ones of the pixels to control the processing of thecolor image data for the pixels using circuitry 16 in accordance withthe respective pixel types. In one arrangement, formatter 14 comprisescircuitry configured to assign pixel identifiers to the respectivepixels and associated with the color image data for the respectivepixels. An object type pixel identifier may be used to indicate a typeof pixel and a type of the color image data associated therewith. Anobject type pixel identifier may be applied to different stagesincluding translating circuits 20, 24 and color space converter core 22of circuitry 16 to control processing of the color image data of therespective pixels within one or more of the stages (e.g., processing ofimage data of a pixel within one or more of circuits 20, 24 and/or core22 may be implemented responsive to the pixel being identified as apredetermined pixel type (text, graphics, line art in illustrativeexamples)).

[0028] For example, circuitry 16 is configured in one embodiment toconvert color image data of an initial color space to an output colorspace wherein black may be represented in different ways (e.g.,different output color space representations). Exemplary differentoutput color space representations of a CMY color space include a firstrepresentation wherein pixels having black color information aregenerated using only CMY colorants (a representation referred to asprocess K), and a second representation wherein pixels having blackcolor information are generated using a single black color (arepresentation referred to as CMYK). As mentioned above, it may bebeneficial in some applications to image pixels having black colorinformation in different ways (i.e., using plural non-black colorants ora single black colorant) corresponding to the different types of pixels.For example, it may be desired to use CMY space to image graphicalpixels while it may desired to use CMYK space to image textual or lineart pixels.

[0029] The pixel identifiers for respective pixels may be assigned inany appropriate manner. For example, if color image data is text dataprovided in PCL or Post Script, formatter 14 may readily identify thepixel types of the pixels associated with the data as text data andaccordingly assign a common text object type identifier. If the colorimage data is provided in compressed JPEG format, the formatter 14 mayreadily identify the pixel types of the pixels associated with the dataas graphical data and accordingly assign a different common graphicalobject type identifier. Formatter 14 may also identify line art colorimage data by a high level language which typically accompanies thecolor image data, and assign an appropriate line art object typeidentifier inasmuch as line art data may be preferably processed as lineart data. The above exemplary distinction of processing between CMY(process K) and CMYK color spaces according to graphical and textcontent is exemplary for illustration purposes and other processingschemes of color image data corresponding to different pixel typesand/or conversion to different plural output color spaces may beprovided.

[0030] Individual pixels may also be identified as NOP pixels wherein nocolor space conversion processing (e.g., translating and/or converting)by circuitry 16 is desired (e.g., translation and/or conversion isbypassed). The color image data of a NOP identified pixel may pass ortravel through circuitry 16 using the indicated exemplary 24 bit buswith no processing being provided by circuitry 20, 22, 24.

[0031] The color image data may be divided according to respectivecolorant bytes and be provided to translating circuitry 20 according tothe division in one exemplary embodiment. For example, the illustratedtranslating circuitry 20 includes a plurality of pairs of addressabletables (e.g., one-dimensional look-up tables (1D LUTs)) 26, 27corresponding to respective ones of cyan, magenta, and yellow inaccordance with the depicted CMY input space example. For a given pixel,a byte of one colorant (cyan) may be provided to one pair of 1D LUTs 26,27, a byte of another colorant (magenta) may be provided to another pairof 1D LUTs 26, 27, and a byte of a third colorant (yellow) may beprovided to the third pair of 1D LUTs 26, 27.

[0032] The object type associated with the pixel being processedcontrols which one of the plurality of 1D LUTs 26, 27 implementstranslating operations for the respective color image data bytes (e.g.,the object type controls which one of the 1D LUTs 26 or 27 of the pairsprovides the processing for the respective bytes). Accordingly, in oneembodiment, the object type selects 1D LUTs 26 or 1D LUTs 27 oftranslating circuitry 20 to implement translating operations for arespective pixel.

[0033] In one possible arrangement, design of the 1D LUTs 26, 27 may beimplemented using a calibration procedure. An input device (e.g.,scanner) used to generate the color image data may be tested using aplurality of predetermined test color patches to determine errorsbetween obtained scanned values resulting from scanning operations andthe known input colors of the test color patches. The 1D LUTs 26, 27 maybe designed using the resultant error information determined from thecalibration. Similarly, 1D LUTs 28, 29 of translating circuitry 24 maybe designed to reduce or minimize errors resulting from a specificbehavior of image engine 18. Additional details regarding exemplarytranslating operations of circuitry 20, 24 are described below.

[0034] In exemplary embodiments, translating circuitry 20 converts anentirety or only portions of individual colorant bytes of color imagedata to translated color image data. In an exemplary embodiment, thetranslating circuitry 20 translates the eight bits of individualcolorant bytes. In another embodiment, only a portion (e.g., four mostsignificant bits) are translated by circuitry 20 and the four leastsignificant bits of individual colorant bytes are passed withouttranslating. The passed least significant bits may be used forinterpolation operations within core 22 in one embodiment.

[0035] Accordingly, translating circuitry 20 operates to translate aportion of the bits of individual pixels of the initial color space inone embodiment. In another arrangement, translating circuitry 20operates to translate all bits of the respective colorants.

[0036] The translating operations of translating circuitry 20, 24 mayimplement different functions. Referring to FIG. 3, an exemplarylinearization translating operation is described. With respect tographical representation 30, color image data is illustrated withrespect to color tones and output values on the respective y and x axes.The depicted exemplary color image data is non-linear in representation30 due to a non-linear response of the color image data input device(e.g., scanner) in one example. Graphical representation 32 representstranslated color image data outputted from translating circuitry 20 andlinearized to correct for the input device response. Accordingly, in oneembodiment, translating circuitry 20 is configured to providelinearization of non-linear values providing substantially linear colorimage data wherein non-linear characteristics of an input color spaceare removed.

[0037] The linearized color image data of graphical representation 32may be applied to RAM address circuitry of color space converter core 22for color space conversion processing as described further below.

[0038] Graphical representation 34 depicts the color image dataoutputted from translating circuitry 24 (also referred to as translatedconverted values). Translating circuitry 24 may return the color imagedata to the original, non-linear response, invert the response (asshown), provide adjustment to data to correct for non-linearcharacteristics of image engine 18 or other output device, and/or beconfigured to provide other desired adjustments to the color image databefore imaging.

[0039] In other embodiments, translating circuitry 20 may also beutilized to expand or compress regions of color image data. For example,processing within color space converter core 22 utilizes interpolationaccording to at least one embodiment. Translating circuitry 20 maycompress some regions of the input color space which are insensitive (orless sensitive) to interpolation errors or approximations and expandother regions of the input color space more sensitive to interpolationerrors or approximations (more sensitive than the some regions).

[0040] More specifically, exemplary interpolation operations accordingto exemplary embodiments are described in U.S. Pat. Nos. 6,049,400 A1;6,040,926 A1; 6,040,925 A1; 6,031,642 A1; 6,028,683 A1; 5,966,474;5,717,507; and 5,666,437, the teachings of which are incorporated hereinby reference. Fixed interpolation intervals over the range of inputvalues may be designated (e.g., 4-bit intervals). Color spaces are oftennot perceptually uniform, and accordingly, some interpolation regionscause more inaccuracies than others (e.g., have increased sensitivity).Utilization of translating circuitry 20 and translating circuitry 24enables a user to compress regions of the color space which arerelatively insensitive to interpolation (e.g., reduce the number ofpossible interpolated output values), and accordingly, to expand regionsthat are relatively sensitive to interpolation (e.g., increase thenumber of possible interpolated output values) to reduce the number oferrors. In particular, the expansion provides additional availableoutput values in sensitive regions (compared with the fixedinterpolation intervals) allowing effectively increased resolution inthe sensitive areas without additional LUT memory locations.

[0041] Referring to FIG. 4, further details of exemplary colorconversion operations of color space converter core 22 includinginterpolation for converting color image data between different colorspaces are described. FIG. 4 shows examples of 3 dimension spaceconversion, other number dimensions may be converted in otherconfigurations. Additional details of operations of color spaceconverter core 22 are described in the patents incorporated by referenceabove. In addition, other configurations may be utilized to implementcolor conversion operations in other embodiments of the invention.

[0042] The exemplary circuitry of core 22 includes RAM address circuitry40, staging flip-flops 42, eight addressable color separation tables(LUTs) 44, staging flip-flops 46 and interpolation stage 48. RAM addresscircuitry 40 is configured to receive the 4 most significant bits of thethree colorant bytes in one embodiment. The 4 least significant bits ofthe bytes are provided to staging flip-flops 42, 46 which provideappropriate timing to provide the unprocessed least significant data tointerpolation stage 48 aligned with the most significant data processedwithin circuitry 40, 44. The least significant data is utilized byinterpolation stage 48 to implement exemplary interpolation operations.

[0043] The entire 24 bits may be passed unprocessed through flip-flops42, 46 to interpolation stage 48 if the current processed pixelcomprises a no operation (NOP) pixel wherein the data is staged fortiming but not processed (e.g., staging of data for a NOP pixel may alsobe provided for translation circuits 20, 24). For a NOP pixel,interpolation stage 48 may strip the two bytes for the other colorantsnot being processed to provide only the 8 bits for the individualcolorant currently being processed using core 22.

[0044] RAM address circuitry 40 operates to address LUTs 44 using themost significant bits of the three bytes for the three colorants of thepixel being processed. LUTs 44 comprise eight LUTs in one exemplaryembodiment configured to provide eight respective vertices of a cubewhich bound the desired output converted value to be determined byinterpolation as described in the patents incorporated by referenceabove.

[0045] In one configuration, the LUTs 44 may be configured to provide aplurality of processing channels corresponding to the respective pixeltypes of the pixels being processed. For example, if one pixel comprisesa text pixel, a first portion of the 8 LUTs 44 may be addressed while ifanother pixel comprises a graphical pixel, a second portion of the 8LUTs 44 may be addressed. Accordingly, RAM address circuitry 40 operatesin one embodiment to select appropriate respective different portions ofthe 8 LUTs 44 for color conversion responsive to the object type orother pixel identifier of the pixel being processed.

[0046] The plurality of channels of the eight LUTs 44 (corresponding tothe pixel types of pixels being processed) may implement different colorspace conversion operations yielding different converted valuescorresponding to the respective channels. For example, a converted valuedetermined using one channel may differ from a converted valuedetermined using a different channel. In addition, the converted valuesresulting from addressing of the different channels may provideconversion (in conjunction with interpolation stage 48) to differentoutput color space representations (e.g., wherein black information isimaged in different ways). In one embodiment, if one pixel is identifiedas a text pixel, conversion to a first output color space representation(CMY process K) may be provided, while if another pixel is identified asa graphical pixel, conversion to a second output color spacerepresentation (CMYK), different than the first output color spacerepresentation, may be provided. Identification of the pixel type (e.g.,using an object type control signal) of a pixel controls RAM addresscircuitry 40 to select the appropriate channel of the 8 LUTs 44 toprovide the desired color space conversion.

[0047] In accordance with exemplary embodiments of the invention, forindividual pixels, identification of the pixel types of the pixelsdictates the respective representation of the output color space towhich the color image data of the pixels will be converted to. For agiven image to be imaged (e.g., upon a single sheet of media) and inaccordance with one embodiment, one portion of the color image data maybe converted to a first output color space representation (correspondingto a first pixel type) and an other portion of the color image data maybe converted to a second different output color space representation(corresponding to a second different pixel type). Accordingly, a firstportion of memory locations of LUTs 44 may be addressed for some pixelsand a second portion of memory locations of LUTs 44 may be addressed forother pixels.

[0048] The LUTs 44 output 8 addressed or otherwise identified values(e.g., bytes) for the appropriate channel and which define the 8vertices of the cube bounding the desired output converted value to bedetermined by interpolation stage 48. Interpolation stage 48 operates tointerpolate the 8 values to define the appropriate converted value to beoutputted from core 22. Interpolation stage 48 additionally implementsthe interpolation operations using the least significant bits staged andaligned with the output of LUTs 44 using staging flip-flops 42, 46. Inone embodiment, the 4 least significant bits of the three colorants areused to interpolate between the 8 vertices to obtain the outputconverted value (e.g., interpolate using the 4 bits in each dimension).

[0049] In accordance with at least one exemplary embodiment, the outputof interpolation stage 48 is applied to output translating circuitry 24of FIG. 2 for further processing to provide translated converted colorimage data as mentioned previously. Alternatively, in anotherembodiment, output translating circuitry 24 may be omitted and theoutput of interpolation stage 48 represents the output converted colorimage data of color space converter circuitry 16 for the respectivecolorant.

[0050] If serial processing using color space converter circuitry 16 isprovided, the obtained value for the respective colorant is stored andprocessing using circuitry 16 is repeated for the other colorants usingthe same input data for the pixel being processed (e.g., in onearrangement the serial processing may be ordered according to: C,M,Y,K).If parallel processing is provided, the parallel values for theindividual color channels are obtained at substantially the same momentin time. The color image data from color space converter circuitry 16 isapplied to appropriate downstream circuitry for any subsequentprocessing (e.g., half toning circuitry not shown) and/or forutilization in the formation of images.

[0051] Referring to FIG. 5, processing of color image data within colorimaging device 10 is described in accordance with one exemplarymethodology. The depicted methodology may be implemented using formatter14, color space converter circuitry 16, image engine 18 or othercomponents in one arrangement. Other methods are possible includingmore, less, or alternative steps.

[0052] At a step S10, color image data to be imaged within device 10 isconverted from a common system-level description to a print language,such as PCL or Post Script. In one arrangement, an external device, suchas a host, coupled with interface circuitry 12 provides the conversionoperations. Step S10 may be omitted in some arrangements (e.g., raw datais provided for example by a scanner).

[0053] At a step S12, the color image data comprising print languagedata is rendered into tone information at a pixel level by formatter 14.Other processing may also be implemented (e.g., scaling raw image datain terms of resolution).

[0054] The processing step S12 may also involve color space conversionto move image elements of the color image data into a common color spaceat a step S14. Step S14 may implement color correction algorithms usinga transfer function of an input device generating the initial colorimage data in one embodiment.

[0055] At a step S16, the color image data may be compressed and storedin a compressed form for printing. The color image data may be storedwithin appropriate memory circuitry (not shown).

[0056] At a step S18, appropriate desired portions of the color imagedata are decompressed for processing and imaging.

[0057] At a step S20, the color image data is color converted into adevice-specific color space and separated into respective planes to beimaged (e.g., CMYK) using color space converter circuitry 16.

[0058] At a step S22, the color image data is halftoned and applied tovideo control inputs of image engine 18 for imaging.

[0059] Different aspects of inventive embodiments are described. Someexemplary aspects provide translating circuitry configured to stretch orcompress appropriate regions of an incoming color space in an effort toprovide usage of interpolated regions in a perceptually uniform way. Inaddition, resulting interpolated data may be independently stretched andcompressed in one or more output color space representations. Theflexibility to modify color image data of an input color space and/orone or more output color space is provided with reduced or noperformance penalties during device operation and with relatively fewadditional hardware resources in at least one embodiment. In addition,the exemplary translating aspects may be implemented and configured by auser as sequential 32-bit words accounting for proper byte-ordering ofvarious processors. In addition, aspects of at least one embodiment ofthe invention facilitates testability, control, and observation of alladdressable tables.

[0060] Other aspects of the disclosed embodiments of color imagingdevices provide increased flexibility in color imaging operations. Forexample, at least one embodiment described herein permits a plurality ofdifferent color space conversion systems to be used. The color imagedata can be processed on a pixel-by-pixel basis wherein individualpixels of a single image may be processed using a plurality of differentcolor treatments, or individual selected pixels of the image may bypassthe color space conversion altogether if desired. Some aspects allowdifferent parts of an image to be processed in different respective waysthat best suit the individual regions of the image. One embodimentprovides selection of different processing on a pixel-by-pixel basiswithin an image, regardless of the compression used or other factors.These advantages may be implemented in one embodiment with a relativelysmall or no adverse impact on throughput, while efficiently utilizinginterpolation and data handling resources.

[0061] Additional exemplary details regarding usage of different colorspace conversion systems are described in a co-pending U.S. patentapplication entitled “Color Imaging Devices, Color Imaging Methods, andColor Separation Methods”, having client docket no. 100110900-1, filedthe same day as the present application, and incorporated by referenceherein.

[0062] The protection sought is not to be limited to the disclosedembodiments, which are given by way of example only, but instead is tobe limited only by the scope of the appended claims.

What is claimed is:
 1. A color imaging device comprising: interfacecircuitry configured to access color image data comprising a pluralityof initial values for a plurality of pixels of a first color space;translating circuitry coupled with the interface circuitry andconfigured to receive the initial values and to provide a plurality ofrespective translated values responsive to the received initial values;color space conversion circuitry coupled with the translating circuitryand configured to convert the translated values to a plurality ofrespective converted values of a second color space different than thefirst color space; and an image engine coupled with the color spaceconversion circuitry and configured to form a color image using theconverted values of the second color space.
 2. The device of claim 1wherein the initial values have a non-linear response, and thetranslating circuitry is configured to provide the translated valuescomprising substantially linear color image data.
 3. The device of claim1 wherein the translating circuitry is configured to linearize the colorimage data of the initial to substantially remove non-linearcharacteristics of the first color space.
 4. The device of claim 1further comprising additional translating circuitry configured totranslate the converted values to provide respective translatedconverted values, and the image engine is configured to form the colorimage using the translated converted values.
 5. The device of claim 1wherein the color space conversion circuitry comprises an addressabletable configured to provide a plurality of respective addressed valuesresponsive to the translated values, and interpolation circuitryconfigured to interpolate the addressed values to provide the respectiveconverted values, and wherein the translating circuitry is configured tocompress some regions of the first color space and to expand otherregions of the first color space which have increased sensitivity tointerpolation errors compared with the some regions.
 6. The device ofclaim 1 wherein the translating circuitry comprises a first tableaddressable using the initial values to provide the translated values,and the color space conversion circuitry comprises a second tableaddressable using the translated values to provide the converted values.7. The device of claim 1 wherein the initial values individually have arespective pixel type corresponding to a respective type of pixel forthe individual value, and wherein the color space conversion circuitryis configured to select respective portions of a plurality ofaddressable tables corresponding to the pixel type of the individualinitial value to convert an individual initial value to a respectivetranslated value.
 8. The device of claim 1 wherein the converted valuesare specific to the color imaging device.
 9. The device of claim 1wherein the image engine comprises a print image configured to form thecolor image as a hard image using media.
 10. A color imaging devicecomprising: means for interfacing for accessing color image datacomprising a plurality of initial values for a plurality of pixels of afirst color space; means for translating for receiving the initialvalues and for providing a plurality of respective translated valuesresponsive to the received initial values; means for color spaceconversion for converting the translated values to a plurality ofrespective converted values of a second color space different than thefirst color space; and means for imaging for forming a color image usingthe converted values of the second color space.
 11. An article ofmanufacture comprising: processor-usable media comprising programmingconfigured to cause processing circuitry to: access color image data fora plurality of pixels of a first color space and corresponding to animage, wherein individual ones of the pixels are one of a plurality ofpixel types; translate the provided color image data of the first colorspace providing translated color image data for the pixels comprising apredetermined pixel type; convert the translated color image data toprovide color image data of a second color space for the pixelscomprising a predetermined pixel type; and output the color image dataof the second color space for use in the generation of color images. 12.A color image forming method comprising: providing a color media imagingdevice; providing color image data for a plurality of pixels of a firstcolor space and corresponding to an image, wherein-individual ones ofthe pixels are one of a plurality of pixel types; translating the colorimage data of the first color space providing translated color imagedata for the pixels comprising a predetermined pixel type; color spaceconverting the translated color image data of the first color space toprovide color image data of a second color space for the pixelscomprising a predetermined pixel type; and providing a plurality ofcolorants upon media according to the color image data of the secondcolor space to form an image.
 13. The method of claim 12 wherein theproviding the color image data comprises providing using an input devicehaving a non-linear response, and the translating comprises linearizingthe color image data of the first color space to provide the translatedcolor image data comprising substantially linear image data.
 14. Themethod of claim 12 wherein the translating comprises linearizing theimage data of the first color space to substantially remove non-linearcharacteristics of the first color space.
 15. The method of claim 12further comprising translating the color image data of the second colorspace before the providing the colorants.
 16. The method of claim 12wherein the color space converting comprises converting using a tablecomprising a plurality of addressable values, and addressing the tableusing the translated color image data to provide the color image data ofthe second color space.
 17. The method of claim 16 wherein thetranslating comprises translating using another table comprising aplurality of addressable values, and further comprising addressing theother table using the color image data of the first color space toprovide the translated color image data.
 18. The method of claim 12wherein the providing the color image data comprises providing the colorimage data comprising a plurality of bits for individual pixels, and thetranslating comprises translating using only a portion of the bits forrespective individual pixels.
 19. The method of claim 12 wherein thecolor space converting comprises converting using a plurality of tables,and for an individual pixel, selecting respective different portions ofthe tables responsive to the respective pixel type of the pixel.
 20. Themethod of claim 12 further comprising identifying at least one pixel asnot comprising a predetermined pixel type, and bypassing the translatingand the color space converting of the color image data for the at leastone pixel responsive to the identifying.
 21. A color image dataprocessing method comprising: providing color image data for a pluralityof pixels of a first color space and corresponding to an image, whereinindividual ones of the pixels are one of a plurality of pixel types;translating the provided color image data of the first color spaceproviding translated color image data for the pixels comprising apredetermined pixel type; color space converting the translated colorimage data to provide color image data of a second color space for thepixels comprising a predetermined pixel type; and outputting the colorimage data of the second color space for use in the generation of colorimages using a color imaging device.
 22. The method of claim 21 whereinthe providing comprises providing using an input device having anon-linear response, and the translating comprises linearizing the colorimage data of the first color space to provide the translated colorimage data comprising linear image data.
 23. The method of claim 21wherein the translating comprises linearizing the image data of thefirst color space to remove non-linear characteristics of the firstcolor space.
 24. The method of claim 21 further comprising translatingthe color image data of the second color space after the color spaceconverting and before the outputting.
 25. The method of claim 21 whereinthe color space converting comprises identifying a plurality of valuesresponsive to the translated color image data, and interpolating thevalues to provide the color image data of the second color space, andwherein the translating comprises compressing some regions of the firstcolor space and expanding other regions of the first color space havingincreased sensitivity to interpolation errors compared with the someregions.
 26. The method of claim 21 wherein the color space convertingcomprises converting using a table comprising a plurality of addressablevalues, and further comprising addressing the table using the translatedcolor image data.
 27. The method of claim 26 wherein the translatingcomprises translating using another table comprising a plurality ofaddressable values, and further comprising addressing the other tableusing the color image data of the first color space.
 28. The method ofclaim 21 wherein the providing comprises providing color image datacomprising a plurality of bits for a plurality of individual pixels, andthe translating comprises translating using only a portion of the bitsfor respective individual pixels.
 29. The method of claim 21 wherein thecolor space converting comprises interpolating the translated colorimage data of individual pixels using one of a plurality ofinterpolation: intervals, and wherein the translating comprises, for anindividual pixel, one of compressing and expanding responsive to thecorresponding interpolation interval.
 30. The method of claim 21 furthercomprising identifying one of a plurality of pixel types for anindividual one of the pixels, and wherein the color space convertingcomprises converting using a plurality of tables, and for the individualpixel, selecting respective portions of the tables responsive to therespective pixel type of the pixel.